4.4.0-57.78) is not available, but a newer one is (4.4.0-142.168). We redirected you there.
/usr/share/man/man9/sx_xunlock.9freebsd.gz is in freebsd-manpages 11.0-1.
This file is owned by root:root, with mode 0o644.
It is a symlink to /usr/share/man/man9/./usr/share/man/man9/SX_SYSINIT.9freebsd.gz